Shafts, such as rotary or drive shafts, are commonly employed for transmitting power from a rotational power source, such as the output shaft of a vehicle transmission, to a rotatably driven mechanism, such as a differential assembly. Oftentimes in power transmission shaft design, shafts are sized such that the material near the center of the shaft provides little benefit in terms of strength. If this is the case, some shafts can be made to be hollow, for example, to reduce weight or material costs. However, in many cases it may be useful to provide conduits for routing fluids such as cooling oil and lubricants within the shaft. When this is the case, typically the shaft designer must leave a suitable amount of material in the center of the shaft to provide for such conduits. As a result, the cost and labor involved in machining of the shaft material may be increased.
Typically, the goal of a transmission design can be to minimize mass and inertia, so a further problem associated with leaving material in the center of the shaft may be that the mass, and thus the inertia, of the shaft cannot be reduced.
Therefore, what is needed is a way to provide a lightweight shaft design that enables the inclusion of various conduits for the routing of fluids and reduces material and machining costs.